A conventional commercial aircraft generally includes a fuselage, a pair of wings, and a propulsion system that provides thrust. The propulsion system typically includes at least two aircraft engines, such as turbofan jet engines. Each turbofan jet engine is typically mounted to a respective one of the wings of the aircraft, such as in a suspended position beneath the wing, separated from the wing and fuselage.
Generally, the turbofan jet engines may be operated in a manner to provide an ability to relatively quickly increase or decrease an amount of thrust output of the engines. For example, prior to a takeoff of the aircraft, the turbofan jet engines are operated at an idle setpoint wherein the turbofan jet engines produce a minimal amount of thrust. Notably, however, the idle setpoint is typically set higher than would otherwise be desirable from a fuel consumption and thrust generation standpoint in order to allow the turbofan jet engines to accelerate relatively quickly when the aircraft is set to takeoff. While setting the idle setpoint at this higher level provides the benefit of increased acceleration at takeoff, it may result in the turbofan jet engines consuming more fuel than is desired and further generating more thrust than is necessary. The higher than desired level of thrust may result in premature wear of the brakes of the aircraft during, e.g., taxiing operations.
Additionally, when operating in a steady state operating condition during flight, active clearance control systems of the turbofan jet engines may close down, or tighten up, clearances within, e.g., respective turbine sections of the turbofan jet engines. As will be appreciated, tightening up the clearances may increase an efficiency of the turbofan jet engines. However, these clearances are not kept as close as would otherwise be desired in order to enable the turbofan jet engines to relatively quickly increase an effective power output if desired. More specifically, these clearances are not kept as close as would otherwise be desired in order to allow the components within the turbofan jet engines to expand radially outwardly if need in response to a command to accelerate the turbofan jet engines (the expansion resulting from, e.g., an increased rotational speed, and/or an increased temperature to which the components are exposed).
Accordingly, a propulsion system for an aircraft capable of operating turbomachines in an efficient manner would be useful.